This invention relates to the subject matter covered in U.S. Pat. No. 4,177,676; of common inventorship herewith. Instrument regulator systems or sensors are typically interconnected with pipelines, pressure vessels and the like for the purpose of sample taking within the vessel. Heretofore, various instrument regulator systems have been employed in pipelines, pressure vessels and the like for the purpose of establishing process interconnection with various instruments such as calorimeters, gravitometers, hydrogen sulfide analyzers and the like. Ordinarily, instrument regulator systems are mounted externally of pipelines, pressure vessels and the like and are communicated with the pressurized fluid therein by means of a suitable passage. Although most instrument regulators are so mounted, the samples that are taken can be in error because they are not taken directly from the pipeline or pressure vessel. In one known case, an instrument regulator has been employed which is interconnected with a pipeline structure in such a manner that an inner portion thereof extends to a position within the pipeline to enable optimum sample taking. A primary problem with instrument regulators is the fact that the pipeline may not be cleaned with internal pipeline scrapers and objects such as pigs, spheres and the like may not pass through the pipeline without first removing the instrument regulator from the pipeline. This problem is also addressed in U.S. Pat. No. 4,177,676. It is desirable, therefore, to provide an instrument regulator system wherein the sample taking probe is adapted for positioning at an optimum sample taking position within the pipeline and, is retractable from the pipeline in order to allow the passage of scrapers, pigs, spheres the other pipeline service equipment through the pipeline.
In many cases, it is desirable that an instrument regulator be capable of removal from the pipeline while the pipeline is maintained under pressure. For example, removal of instrument regulators under pressure is accomplished to facilitate running of pigs through the pipeline and to do simple maintenance on the regulator system without blowing down the pipeline. Installation and removal of instrument regulators and other such sensors while a pipeline is maintained under pressure is also important. For example, it may be desirable to facilitate installation of instrument regulator through a "hot tap" into a section of pipeline that cannot be blown down. The instrument servicing operations may be carried out without necessitating shutting down of the flow system or process, thereby saving the production losses that would otherwise result.